Adrenal Medulla - Function & Diseases

Adrenal Medulla - Function & Diseases

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:14 PM IST

The adrenal medulla is a part of the adrenal gland that secretes important hormones which regulate the fight or flight response in the body. These hormones mainly include adrenaline, known as epinephrine, and noradrenaline, which is also called norepinephrine, playing a very significant role in many stress responses. In this article, the adrenal medulla, anatomy of adrenal glands, the structure of the adrenal medulla, functions of the adrenal medulla, disorders of the adrenal medulla, diagnosis and treatment of disorders of the adrenal medulla, and role in stress response are discussed. Adrenal Medulla is a topic of the chapter Chemical Coordination and Integration chapter of Biology.

This Story also Contains
  1. What is the Adrenal Medulla?
  2. Anatomy of Adrenal Glands
  3. Structure of Adrenal Medulla
  4. Adrenal Medulla Hormones
  5. Functions of the Adrenal Medulla
  6. Disorders of the Adrenal Medulla
  7. Diagnosis and Treatment of Disorders of Adrenal Medulla
  8. Role in Stress Response
Adrenal Medulla - Function & Diseases
Adrenal Medulla - Function & Diseases

What is the Adrenal Medulla?

The adrenal medulla represents a small triangular structure topping each kidney and forming the inner portion of adrenal glands. It accounts for 10% of the weight of the gland and is covered by the adrenal cortex. The medulla produces those hormones essential for the body's response to stressful conditions, thus maintaining physiological balance.

Anatomy of Adrenal Glands

There are two main divisions of the adrenal glands:

  • The outer region, or adrenal cortex, is the largest part of the gland. It has three subdivisions that produce different hormones; zona glomerulosa, zona fasciculata, and zona reticularis.
  • The section situated inside the cortex is the adrenal medulla. It is responsible for producing adrenaline, which is also known as the stress hormone.

Both regions are surrounded by an adipose capsule, which serves as a protective covering for the adrenal gland.

There are some specific cellular features of the adrenal medulla. They are:

  • In order to regulate adrenal medulla hormones, a specific blood supply is required.

  • The system of nerves known as the "greater splanchnic nerve" supports medullary communication with other parts of the body.

  • The chromaffin cells possess tiny granules that are released when the splanchnic nerve cells activate a response to stress. This signal leads to the circulation of adrenaline and noradrenaline in the blood.

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Adrenal medulla

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Structure of Adrenal Medulla

The adrenal medulla is centrally located within the adrenal glands and is characterized by:

Chromaffin Cells

Such cells are rather crucial in producing hormones. They will be irregularly shaped and located near blood vessels, thus allowing for the secretion of hormones into the bloodstream.

Cell Organisation

These chromaffin cells lie anatomic ally and functionally fine near blood vessels so that their release from the body takes place efficiently. They also connect with the autonomic nervous system which aids in regulating their activity.

Adrenal Medulla Hormones

There are several important hormones produced in the adrenal medulla:

Epinephrine (Adrenaline)

This is released during stressful conditions. This peptide hormone increases heart rate, shifts blood flow to the muscles and the brain, and increases blood sugar to raise quick response.

Roles of Adrenaline

Adrenaline is released by the medulla as a response to low blood sugar levels or while the body is in work or exercise mode. It shows a reaction to stress by body mechanisms such as:

  • It helps by sending oxygen to muscles at high levels.

  • It controls the rise in blood pressure and the required heart rate.

  • It widens the small arteries for easy blood circulation.

Norepinephrine (Noradrenaline)

Vasoconstriction is a reduced diameter of the blood vessels caused due to norepinephrine. Along with epinephrine, it increases blood pressure. The activities involve the body's 'fight or flight' response, usually including the maintenance of cardiac function.

Role of Noradrenaline

Noradrenaline causes the body to respond to stress by causing the following changes:

  • It causes an increase in blood sugar levels.

  • The blood vessels are narrowed down as required.

  • It causes a rise in blood pressure levels.

  • It also takes part in the brain’s function of storing memories.

  • It supports us in waking up.

  • It supports emotional abilities and health.

  • It gives us the strength to pay attention and be focused.

Dopamine

This catecholamine is produced in smaller amounts and represents the precursor to norepinephrine. It has an action on neurotransmission, mood, and regulation of motor control.

Functions of the Adrenal Medulla

The major functions of the adrenal medulla are

Fight or Flight Response

It makes hormones like epinephrine and norepinephrine following the receipt of the 'stress' signal from the sympathetic nervous system. With its stimulation, it readies the body for immediate action with a racing heartbeat, blood supply to the muscles, and loads of energy.

Hormone Conversion

The medulla is concerned with the conversion of the amino acid tyrosine to epinephrine and norepinephrine. This function is vital in keeping up the 'preparedness' of the body to meet stress.

Disorders of the Adrenal Medulla

The disorders of Adrenal Medulla include:

Pheochromocytoma

This is the most common disorder directly related to the adrenal medulla. The literal meaning is a tumour of chromaffin cells causing excess production of epinephrine and norepinephrine. Common symptoms include high blood pressure, tachycardia and sweating.

Diagnosis and Treatment of Disorders of Adrenal Medulla

Pheochromocytoma and such related disorders are diagnosed based on the measurements of hormone levels from blood and urine, imaging studies like CT scans or MRIs, and biopsy if necessary.

Treatment

This is mostly done through surgical removal of the tumour. At times medication is given before surgery which would lessen symptoms due to the controlled amount of hormones.

Role in Stress Response

It is because of the adrenal medulla that, during instances of acute stress, the human body gets its share of catecholamines, responsible for adjustments to be made in a range of physiological functions so that the organism receives properly set for an impending challenge.

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Frequently Asked Questions (FAQs)

1. Define the adrenal medulla.

The medulla is the innermost section of the adrenal gland. Its primary function is to secrete hormones in response to stressors.

2. Mention the parts of the adrenal gland.

The smaller part of the gland is the medulla, and the outer part is the adrenal cortex. The adrenal cortex makes up the largest area of the gland.

3. Where are the adrenal glands situated in the body?

There are two adrenal glands on the top of both kidneys, just below the ribcage.

4. Name a disease caused by adrenal oversecretion.

Conn syndrome is caused by adrenal oversecretion.

5. What are the types of tumours caused inside the adrenal glands?

There are two types of tumours that develop inside the adrenal glands: benign and carcinogenic.

6. What is the function of the adrenal medulla?

The adrenal medulla secretes adrenaline (epinephrine) and noradrenaline (norepinephrine), hormones that help the body respond to stress by increasing heart rate, blood pressure, and energy availability.

7. What is the adrenal medulla an important part of?

The adrenal medulla is an essential part of the adrenal glands, which are part of the endocrine system. It plays a critical role in the body’s fight-or-flight response during stress.

8. What is the adrenal medulla cell called?

The primary cells of the adrenal medulla are called chromaffin cells. These cells produce and release adrenaline and noradrenaline directly into the bloodstream.

9. What is the disease of the adrenal medulla?

A common disease of the adrenal medulla is pheochromocytoma, a rare tumour that causes excessive production of adrenaline and noradrenaline, leading to high blood pressure and other symptoms related to overstimulation of the sympathetic nervous system.

10. What are the primary hormones produced by the adrenal medulla?
The adrenal medulla primarily produces two catecholamine hormones: epinephrine (adrenaline) and norepinephrine (noradrenaline). These hormones play crucial roles in the body's stress response and regulation of various physiological processes.
11. How does the adrenal medulla contribute to the body's response to hypoglycemia?
The adrenal medulla is a key player in the body's defense against hypoglycemia (low blood sugar). When blood glucose levels fall, the adrenal medulla releases epinephrine, which stimulates glucose production and release from the liver, and reduces glucose uptake by peripheral tissues, helping to restore normal blood sugar levels.
12. What is the adrenal medulla and where is it located?
The adrenal medulla is the inner region of the adrenal gland, located on top of each kidney. It is surrounded by the adrenal cortex and is part of the endocrine system, producing and secreting hormones directly into the bloodstream.
13. What is pheochromocytoma and how does it relate to the adrenal medulla?
Pheochromocytoma is a rare tumor that develops in the adrenal medulla's chromaffin cells. It causes excessive production of catecholamines, leading to symptoms like high blood pressure, rapid heartbeat, sweating, and anxiety. This condition highlights the importance of balanced adrenal medulla function.
14. How does the function of the adrenal medulla change with age?
As people age, the responsiveness of the adrenal medulla may decrease. This can result in a reduced capacity to respond quickly to stress, potentially affecting cardiovascular function and energy mobilization. However, baseline levels of catecholamines may actually increase with age due to reduced clearance.
15. What is adrenal medullary hyperplasia and how does it affect hormone production?
Adrenal medullary hyperplasia is a condition where the adrenal medulla becomes enlarged due to an increase in the number of chromaffin cells. This can lead to overproduction of catecholamines, causing symptoms similar to those of pheochromocytoma, such as high blood pressure and rapid heart rate.
16. What is the connection between the adrenal medulla and panic attacks?
Panic attacks are often associated with sudden, intense activation of the adrenal medulla. The surge of epinephrine and norepinephrine can cause physical symptoms like rapid heartbeat, sweating, and shortness of breath. Understanding this connection helps in managing panic disorders through various therapeutic approaches.
17. How does the adrenal medulla respond to chronic stress?
Under chronic stress, the adrenal medulla may initially increase catecholamine production. However, prolonged activation can lead to adrenal fatigue, where the gland's ability to produce hormones becomes impaired. This can result in reduced stress tolerance and various health issues.
18. What is the relationship between the adrenal medulla and cardiovascular health?
The adrenal medulla plays a significant role in cardiovascular function. While short-term activation is normal and adaptive, chronic overactivation of the adrenal medulla can contribute to cardiovascular problems like hypertension, arrhythmias, and increased risk of heart disease due to the persistent effects of catecholamines on the heart and blood vessels.
19. What is the role of the adrenal medulla in regulating blood sugar in diabetes?
In diabetes, the function of the adrenal medulla becomes particularly important. The catecholamines it produces can counteract the effects of insulin, raising blood glucose levels. This can make blood sugar management more challenging for diabetics, especially during stress when adrenal medulla activity increases.
20. How does the adrenal medulla influence the sleep-wake cycle?
The adrenal medulla plays a role in regulating the sleep-wake cycle. Catecholamine levels naturally fluctuate throughout the day, with higher levels in the morning contributing to wakefulness. Overactivity of the adrenal medulla, such as in chronic stress, can disrupt this cycle, potentially leading to sleep disorders.
21. How does the adrenal medulla affect skin function?
Hormones from the adrenal medulla influence skin function in several ways. They cause vasoconstriction in the skin, which can lead to paleness. They also stimulate sweat glands, increasing perspiration. In some people, these effects can contribute to skin conditions like hyperhidrosis (excessive sweating) or exacerbate symptoms of certain skin disorders.
22. How does the adrenal medulla interact with the immune system?
Hormones from the adrenal medulla can modulate immune function. In the short term, they can enhance certain aspects of immunity. However, chronic elevation of these hormones (as in prolonged stress) can suppress immune function, potentially increasing susceptibility to infections and other health issues.
23. What is the role of the adrenal medulla in regulating blood pressure?
The adrenal medulla helps regulate blood pressure through the release of epinephrine and norepinephrine. These hormones cause vasoconstriction (narrowing of blood vessels) in many parts of the body, which increases blood pressure. They also increase heart rate and contractility, further contributing to blood pressure regulation.
24. How does the adrenal medulla contribute to the regulation of body temperature?
Hormones released by the adrenal medulla, especially epinephrine, can increase metabolic rate and heat production in the body. They also cause peripheral vasoconstriction, which helps conserve heat. In some animals, these hormones can stimulate brown fat tissue to generate heat, a process known as non-shivering thermogenesis.
25. How does the adrenal medulla affect blood glucose levels?
Hormones released by the adrenal medulla, particularly epinephrine, increase blood glucose levels through several mechanisms. They stimulate the liver to break down glycogen into glucose (glycogenolysis) and promote the production of new glucose (gluconeogenesis). Additionally, these hormones reduce insulin sensitivity in peripheral tissues, further elevating blood glucose levels.
26. How does the adrenal medulla affect digestion?
Hormones from the adrenal medulla generally inhibit digestive processes. They reduce blood flow to the digestive system, decrease gastric motility, and inhibit digestive secretions. This allows the body to divert energy and resources to more critical functions during stress or emergencies.
27. What is the difference between the effects of the adrenal medulla and the adrenal cortex?
While both are part of the adrenal gland, they have distinct functions. The adrenal medulla produces catecholamines (epinephrine and norepinephrine) for rapid, short-term stress responses. The adrenal cortex produces steroid hormones like cortisol for longer-term stress adaptation, as well as aldosterone for electrolyte balance and androgens for secondary sex characteristics.
28. How do epinephrine and norepinephrine differ in their functions?
While both hormones have similar effects, epinephrine generally has a more widespread impact. Epinephrine increases heart rate, blood pressure, and blood glucose levels, while also dilating airways. Norepinephrine primarily affects blood pressure by constricting blood vessels. Both hormones prepare the body for immediate action in stressful situations.
29. What triggers the release of hormones from the adrenal medulla?
The release of hormones from the adrenal medulla is triggered by nerve impulses from the sympathetic nervous system. This occurs in response to stress, fear, or excitement, activating the "fight or flight" response.
30. How does the adrenal medulla contribute to the body's stress response?
The adrenal medulla plays a crucial role in the body's acute stress response by rapidly releasing epinephrine and norepinephrine. These hormones increase heart rate, blood pressure, and blood glucose levels, while also enhancing alertness and focus, preparing the body to respond to perceived threats or challenges.
31. What is the relationship between the adrenal medulla and the sympathetic nervous system?
The adrenal medulla is often referred to as a "modified sympathetic ganglion" because it is innervated by preganglionic sympathetic neurons. When the sympathetic nervous system is activated, it stimulates the adrenal medulla to release its hormones, effectively extending the reach and duration of the sympathetic response.
32. How does the adrenal medulla influence respiratory function?
Hormones from the adrenal medulla, particularly epinephrine, cause bronchodilation (widening of airways) in the lungs. This increases airflow and oxygen uptake, preparing the body for increased physical activity during stress or emergencies.
33. What is the relationship between the adrenal medulla and the "fight or flight" response?
The adrenal medulla is a key component of the "fight or flight" response. When activated by the sympathetic nervous system, it rapidly releases epinephrine and norepinephrine, which trigger physiological changes that prepare the body for immediate action, such as increased heart rate, elevated blood pressure, and enhanced alertness.
34. How does the adrenal medulla affect liver function?
Catecholamines from the adrenal medulla have important effects on the liver. They stimulate glycogenolysis (breakdown of glycogen to glucose) and gluconeogenesis (production of new glucose), both of which increase blood glucose levels. They also influence other metabolic processes in the liver, adapting its function to meet the body's energy needs during stress.
35. What is the role of the adrenal medulla in thermoregulation during fever?
During fever, the adrenal medulla contributes to raising and maintaining body temperature. Catecholamines released by the adrenal medulla increase metabolic rate and heat production. They also cause peripheral vasoconstriction, which helps retain heat. This complements other fever-inducing mechanisms to elevate body temperature as part of the immune response.
36. How does the adrenal medulla influence gastrointestinal motility?
Catecholamines from the adrenal medulla generally inhibit gastrointestinal motility. They reduce smooth muscle contractions in the digestive tract, slowing down the movement of food. This is part of the body's stress response, diverting energy from digestive processes to more immediately vital functions during times of perceived threat or emergency.
37. What is the relationship between the adrenal medulla and the hypothalamic-pituitary-adrenal (HPA) axis?
While the adrenal medulla is primarily controlled by the sympathetic nervous system, it also interacts with the HPA axis. Catecholamines from the adrenal medulla can influence the release of corticotropin-releasing hormone (CRH) from the hypothalamus and adrenocorticotropic hormone (ACTH) from the pituitary, thus indirectly affecting cortisol production by the adrenal cortex.
38. What is the "adrenaline rush" and how is it related to the adrenal medulla?
An "adrenaline rush" refers to the sudden surge of epinephrine (adrenaline) released by the adrenal medulla in response to stress or excitement. This causes rapid physiological changes like increased heart rate, heightened alertness, and a burst of energy, preparing the body for intense physical activity or mental focus.
39. How does the adrenal medulla affect pupil dilation?
Catecholamines released by the adrenal medulla cause pupil dilation (mydriasis) by stimulating the dilator muscles of the iris. This allows more light into the eyes, potentially improving vision in low-light conditions during stress or emergencies.
40. What is the role of the adrenal medulla in fetal development?
During fetal development, the adrenal medulla plays a crucial role in preparing the fetus for extrauterine life. It undergoes significant growth and maturation in late gestation, and the surge of catecholamines during birth helps the newborn adapt to life outside the womb by regulating blood pressure, stimulating breathing, and mobilizing energy reserves.
41. How does the adrenal medulla affect muscle function during stress?
Hormones from the adrenal medulla increase blood flow to skeletal muscles, enhance glucose uptake, and promote the breakdown of glycogen in muscle tissue. This provides muscles with more energy and oxygen, improving strength and endurance for short-term, high-intensity activities.
42. What is the connection between the adrenal medulla and exercise performance?
The adrenal medulla contributes significantly to exercise performance. During physical activity, it releases catecholamines that increase heart rate, blood pressure, and blood flow to muscles. These hormones also mobilize energy reserves and enhance muscle strength and endurance, allowing for improved athletic performance, especially in high-intensity activities.
43. How does the structure of the adrenal medulla relate to its function?
The adrenal medulla is composed of chromaffin cells, which are modified postganglionic neurons. This structure allows the adrenal medulla to respond quickly to nerve impulses from the sympathetic nervous system, releasing hormones that prepare the body for "fight or flight" responses.
44. What is the role of the adrenal medulla in the body's response to hemorrhage?
In response to hemorrhage (severe blood loss), the adrenal medulla releases large amounts of catecholamines. These hormones cause vasoconstriction to maintain blood pressure, increase heart rate to improve circulation, and stimulate the spleen to release stored red blood cells. This response is crucial for short-term survival during acute blood loss.
45. How does the adrenal medulla contribute to the regulation of blood pH?
The adrenal medulla indirectly
46. How does the adrenal medulla affect blood coagulation?
Catecholamines from the adrenal medulla can influence blood coagulation. They generally promote blood clotting by increasing platelet aggregation and activating certain coagulation factors. This effect can be adaptive in cases of injury but may also contribute to increased risk of thrombosis in conditions of chronic stress or adrenal medulla overactivity.
47. What is the relationship between the adrenal medulla and catecholamine-secreting tumors outside the adrenal gland?
While the adrenal medulla is the primary source of circulating catecholamines, tumors called paragangliomas can develop from chromaffin tissue outside the adrenal glands. These tumors can secrete catecholamines, causing symptoms similar to those of adrenal medullary tumors. Understanding this relationship is important for diagnosing and treating catecholamine-related disorders.
48. How does the adrenal medulla contribute to the regulation of metabolism?
The adrenal medulla plays a significant role in metabolic regulation. Catecholamines increase metabolic rate, stimulate breakdown of glycogen and fat for energy, and promote glucose production. They also influence insulin and glucagon secretion, playing a key role in maintaining energy balance, especially during stress or fasting.
49. What role does the adrenal medulla play in cognitive function?
Catecholamines released by the adrenal medulla can enhance cognitive function, particularly during stress. They increase alertness, improve focus and attention, and can enhance memory formation for emotionally significant events. This cognitive boost is part of the body's adaptive response to challenging situations.
50. How does the adrenal medulla contribute to the body's pain response?
Hormones from the adrenal medulla can modulate pain perception. They can increase the pain threshold in acute stress situations, contributing to the phenomenon of stress-induced analgesia. This temporary reduction in pain sensitivity can be adaptive in dangerous situations requiring immediate action.
51. What is the connection between the adrenal medulla and bronchial asthma?
The adrenal medulla plays a complex role in bronchial asthma. While epinephrine can help relieve asthma symptoms by dilating airways, chronic stress and overactivation of the adrenal medulla may contribute to airway inflammation and hypersensitivity. Understanding this relationship is important in managing asthma, especially stress-induced symptoms.
52. How does the adrenal medulla affect kidney function?
Hormones from the adrenal medulla influence kidney function in several ways. They can decrease blood flow to the kidneys by causing vasoconstriction of renal blood vessels. They also affect sodium reabsorption and can influence renin release, indirectly impacting blood pressure regulation through the renin-angiotensin-aldosterone system.
53. What is the role of the adrenal medulla in adaptation to high altitude?
The adrenal medulla plays a crucial role in the body's adaptation to high altitude. Increased catecholamine release helps compensate for lower oxygen levels by increasing heart rate, respiratory rate, and red blood cell production. This response aids in maintaining adequate oxygen delivery to tissues in the low-oxygen environment of high altitudes.

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